Wireless communication method and device

ABSTRACT

Provided are wireless communication methods and devices. In one embodiment, a wireless communication method performed by a wireless communication device comprises: transmitting a data packet repeatedly in multiple subframes including at least one normal subframe and at least one special subframe to another wireless communication device, wherein the available resources in the special subframe are different from that in the normal subframe, the data packet includes multiple modulated symbols which are divided into multiple modulated-symbol sets, in each subframe, each OFDM symbol is mapped by one of the modulated-symbol sets, and in every subframe, the modulated symbols in the same modulated-symbol set are mapped onto REs in one OFDM symbol in a fixed order. In another embodiment, multiple repetitions of the data packet are transmitted in each subframe, and in each special subframe, different repetitions are mapped onto REs with cyclic shift.

BACKGROUND 1. Technical Field

The present disclosure relates to the field of wireless communication,and in particular, to wireless communication methods and wirelesscommunication devices such as an eNode B (eNB) or user equipment (UE).

2. Description of the Related Art

Machine-Type Communication (MTC) is an important revenue stream foroperators and has a huge potential from the operator perspective. Basedon the market and operators' requirements, one of the importantrequirements of MTC is improving the coverage of pieces of MTC UE. Toenhance the MTC coverage, almost all of the physical channels need to beenhanced. Repetition in time domain is the main method to improve thecoverage of the channels. At the receiver side, the receiver combinesall the repetitions of the channel and decodes the information.

In Time Division Duplexing (TDD), not all the subframes in one frame areused for downlink (DL) or uplink (UL) transmission. According to theframe structure in LTE specification, there are DL subframes, ULsubframes and special subframes in one frame. In a special subframe, itincludes DwPTS, GP and UpPTS, as shown in FIG. 1 which schematicallyillustrates the structure of a special subframe in TDD. Downlink channelcan be transmitted in DwPTS, and uplink channel can be transmitted inUpPTS.

For different special subframe configurations, the lengths of DwPTS andUpPTS are different. Take DwPTS for example, the lengths of DwPTSaccording to the special subframe configurations are listed in the tablebelow (Table 1).

TABLE 1 Normal cyclic prefix in downlink DwPTS Special subframeconfiguration (number of OFDM symbols) 0 3 1 9 2 10 3 11 4 12 5 3 6 9 710 8 11 9 6

For MTC in coverage enhancement mode, the repetitions of one channel aretransmitted in multiple subframes. To fully use the downlink or uplinkresource and reduce the latency, it is better to also use DwPTS or UpPTSto transmit downlink or uplink channel repetitions. As the availableresources in the special subframe are different from that in the normalsubframe, how to map repetition in DwPTS or UpPTS in a special subframebecomes a problem.

SUMMARY

In one general aspect, the techniques disclosed here feature a wirelesscommunication method performed by a wireless communication device,comprising: transmitting a data packet repeatedly in multiple subframesincluding at least one normal subframe and at least one special subframeto another wireless communication device, wherein the availableresources in the special subframe are different from that in the normalsubframe, the data packet includes multiple modulated symbols which aredivided into multiple modulated-symbol sets, in each subframe, eachOrthogonal Frequency Division Multiplexing (OFDM) symbol is mapped byone of the modulated-symbol sets, and in every subframe, the modulatedsymbols in the same modulated-symbol set are mapped onto ResourceElements (REs) in one OFDM symbol in a fixed order.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates the structure of a special subframe inTDD;

FIG. 2 schematically illustrates a flowchart of a wireless communicationmethod at the transmitting side according to a first embodiment of thepresent disclosure;

FIG. 3 schematically illustrates an example of resource mappingaccording to the first embodiment;

FIG. 4 schematically illustrates exemplary resource mapping consideringCRS according to an example of the first embodiment;

FIG. 5 schematically illustrates exemplary resource mapping consideringDMRS according to an example of the first embodiment;

FIG. 6 schematically illustrates exemplary resource mapping consideringboth CRS and DMRS according to an example of the first embodiment;

FIG. 7 schematically illustrates exemplary cyclic resource mappingaccording to an example of the first embodiment;

FIG. 8 schematically illustrates an example of handling RS REs accordingto an example of the present disclosure;

FIG. 9 schematically illustrates a block diagram of a wirelesscommunication device at the transmitting side according to the firstembodiment;

FIG. 10 schematically illustrates a flowchart of a wirelesscommunication method at the receiving side according to the firstembodiment of the present disclosure;

FIG. 11 schematically illustrates a block diagram of a wirelesscommunication device at the receiving side according to the firstembodiment;

FIG. 12 schematically illustrates multiple repetitions transmitted inone subframe; and

FIG. 13 illustrates an example of resource mapping with cyclic shiftaccording to a second embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part thereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. It will be readily understood that the aspects ofthe present disclosure can be arranged, substituted, combined, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated and make part of this disclosure.

In the present disclosure, wireless communication methods performed bywireless communication devices are provided. Herein, the wirelesscommunication methods can be applied to any type of wirelesscommunications, for example but not limited to communications conformingto LTE specifications, MTC. Similarly, the wireless communicationdevices can be any devices with wireless communication function such aseNBs or pieces of UE. In addition, in the following description, TDD anddownlink transmission may be taken as examples to explain the presentdisclosure; however, it is noted that the present disclosure is notlimited to TDD and downlink transmission but can also be applied to FDDand uplink transmission.

First Embodiment

In the first embodiment of the present disclosure, there is provided awireless communication method 200 performed by a wireless communicationdevice (first wireless communication device), as shown in FIG. 2 whichschematically illustrates the flowchart of the wireless communicationmethod 200 according to the first embodiment. The wireless communicationmethod 200 comprises a step 201 of transmitting a data packet repeatedlyin multiple subframes including at least one normal subframe and atleast one special subframe to another wireless communication device(second communication device). In this communication method, the datapacket is transmitted repeatedly in multiple subframes in order toenhance the physical channel. This repeated transmission is inparticular suitable for MTC, but not limited to MTC. It can be appliedto any wireless communication requiring channel enhancement. The firstcommunication device and the second communication device can be an eNB,a UE or the like depending on specific application scenarios. Forexample, if the communication method is applied to downlinkcommunication, the first communication device can be an eNB or the like,and the second communication device can be a UE or the like. Similarly,if the communication method is applied to uplink communication, thefirst communication device can be an UE or the like, and the secondcommunication device can be an eNB or the like. In the first embodiment,the repeated transmission is performed in two kinds of subframes whichare the normal subframe and the specific subframe. The normal subframeand the specific subframe herein can be that defined according to theframe structure in LTE specifications; however, the normal subframe andthe specific subframe herein can also be defined otherwise so far as theavailable resources in the special subframe are different from that inthe normal subframe.

In the first embodiment, the data packet includes multiple modulatedsymbols, and these modulated symbols are divided into multiplemodulated-symbol sets. In each subframe, each Orthogonal FrequencyDivision Multiplexing (OFDM) symbol is mapped by one of themodulated-symbol sets, and in every subframe, the modulated symbols inthe same modulated-symbol set are mapped onto Resource Elements (REs) inone OFDM symbol in a fixed order.

FIG. 3 schematically illustrates an example of resource mappingaccording to the first embodiment. The left subfigure in FIG. 3 showsresource mapping of a normal subframe, and the right subfigure showsresource mapping of a special subframe. The data packet to betransmitted includes multiple modulated symbols which are mapped ontoREs in a subframe respectively. As shown in the normal subframe of FIG.3, there are 132 modulated symbols #0-131 in the data packet which aremapped onto 132 REs in the DL channel of the normal subframe. The 132modulated symbols are divided into 11 modulated-symbol sets which aresets #0-10, and each set is mapped onto one OFDM symbol in the normalsubframe, i.e. one column in the left subfigure of FIG. 3. For example,set #0 including modulated symbols #0-#11 is mapped onto the first(leftmost) OFDM symbol of the repeated DL channel of the normalsubframe, set #1 including modulated symbols #12-23 is mapped onto thesecond OFDM symbol of the repeated DL channel of the normal subframe,and so on. In this example, one complete repetition of the data packetcan be transmitted in one normal subframe.

For a special subframe, the available resources for DL transmission inDwPTS may be less than that in the normal because some resources may beused for GP and UpPTS; therefore, one special subframe may not be ableto transmit one complete repetition of the data packet. In this case, apart of the modulated symbols of the data packet are transmitted in onespecial subframe. However, the above resource mapping rule according tothe first embodiment can also be applied to the special subframe, thatis, in each subframe, each OFDM symbol is mapped by one of themodulated-symbol sets. For example, as shown in the right subfigure ofFIG. 3, set #0 including modulated symbols #0-#11 is mapped onto thefirst (leftmost) OFDM symbol of the repeated DL channel of the specialsubframe, set #1 including modulated symbols #12-#23 is mapped onto thesecond OFDM symbol of the repeated DL channel of the special subframe,and so on.

In addition, according to the first embodiment, in every subframe, themodulated symbols in the same modulated-symbol set are mapped onto REsin one OFDM symbol in a fixed order. In other words, for all thesubframes for repeatedly transmitting the data packet, the modulatedsymbols in the same set are mapped onto respective subcarriers in thesame order no matter the subframe is a normal subframe or a specialsubframe. For example, for the set #0 including modulated symbols #0-11in the FIG. 3, for both the normal subframe and the special subframe,the modulated symbols #0-11 are mapped onto REs of the OFDM subframefrom the top to the bottom. In other words, the same or fixed mappingorder is used for both the normal subframe and the special subframe.According to the first embodiment, the mapping order is the same for allthe subframes for repeatedly transmitting the data packet (i.e., everysubframe).

According to the first embodiment of the present disclosure, since onemodulated symbol set is mapped onto one OFDM symbol in each subframe andthe modulated symbols in the same modulated-symbol set are mapped ontoREs in one OFDM symbol in a fixed order in every subframe, the samemodulated symbol will be mapped onto the same subcarrier in differentrepetitions or subframes. Therefore, the symbol level combining at thereceiver side becomes possible. Using the symbol level combining, thereceiver needs not to do channel estimation, channel equalization anddemodulation of each repetition. This will reduce the complexity andpower consumption of the pieces of UE, in particular, pieces of MTC UE,which is the main requirement of pieces of MTC UE or many other piecesof UE.

It is noted that, FIG. 3 takes the downlink transmission as an examplein which the data packet is transmitted in DwPTS when it is transmittedin the special subframe, but the first embodiment can also be applied touplink transmission in which the data packet can be transmitted in UpPTSwhen it is transmitted in the special subframe. In addition, if theavailable OFDM symbols for the transmission in a special subframe issmaller than that in a normal subframe, a part of the modulated symbolsof the data packet are transmitted in one special subframe, and all themodulated symbols of the data packet can be transmitted cyclically indifferent special subframes. For example, sets #0-4 are transmitted inthe first special subframe, sets #5-9 are transmitted in the secondspecial subframe, set #10 and sets #0-3 are transmitted in the thirdspecial subframe, and so on. In this manner, all the modulated symbolscan obtain balanced repetition gain. However, alternatively, it ispossible to always truncate the same part of the modulated symbols to betransmitted in different special subframes.

Further, as an improvement to the first embodiment, reference signals(RSs) are to be considered in the resource mapping. In an exemplaryembodiment, the modulated-symbol set transmitted in an OFDM symbol withRSs in the normal subframe can be also transmitted in an OFDM symbolwith the RSs in a special subframe (e.g., in DwPTS). It is noted thatthe RSs in the normal subframe and the RSs in the special subframe hererefer to the same kind of RS. For example, the modulated-symbol settransmitted in an OFDM symbol with CRS in the normal subframe is alsotransmitted in an OFDM symbol with CRS in DwPTS, and similarly themodulated-symbol set transmitted in an OFDM symbol with DMRS in thenormal subframe is also transmitted in an OFDM symbol with DMRS inDwPTS. In addition, if the number of the OFDM symbols with the RSs inDwPTS is less than that in the normal downlink subframe, themodulated-symbol sets transmitted in OFDM symbols with the RSs in thenormal downlink subframe may be transmitted cyclically in OFDM symbolswith the RSs in DwPTS of multiple special subframes. And, themodulated-symbol sets transmitted in OFDM symbols without any RS in anormal downlink subframe may be transmitted cyclically in OFDM symbolswithout any RS in DwPTS of multiple special subframes.

FIG. 4 schematically illustrates exemplary resource mapping consideringCRS according to an example of the first embodiment. In this example,the modulated-symbol set transmitted in an OFDM symbol with CRS in thenormal subframe is transmitted in an OFDM symbol with CRS in DwPTS. Thefour subfigures of FIG. 4 are the normal DL subframe, the specialsubframe #1, the special subframe #2, and the special subframe #3respectively, in which the dotted REs represent the CRS positions (REs).It can be seen that the modulated-symbol set consisting of the modulatedsymbols #0-7, the modulated-symbol set consisting of the modulatedsymbols #32-39, and the modulated-symbol set consisting of the modulatedsymbols #76-83 are mapped onto OFDM symbols with CRS (the OFDM symbols#4, #7 and #11) in the normal subframe respectively, and thosemodulated-symbol sets are also mapped onto OFDM symbols with CRS (theOFDM symbols #4 and #7) in the special subframes. In addition, in thisexample, since the number of the OFDM symbols with CRS in DwPTS of thespecial subframes is less than that in the normal DL subframe, themodulated-symbol sets transmitted in OFDM symbols with CRS in the normaldownlink subframe are transmitted cyclically in OFDM symbols with CRS inDwPTS of multiple special subframes. As shown in FIG. 4, the specialsubframe #2 transmits the set consisting of the modulated symbols #0-7again after finishing the transmission of the set consisting of themodulated symbols #76-83. In addition, optionally, the modulated-symbolsets transmitted in OFDM symbols without CRS in the normal downlinksubframe can be transmitted cyclically in OFDM symbols without CRS inDwPTS. According to the example shown in FIG. 4, the performanceimbalance among the modulated symbols transmitted in OFDM symbols withCRS is alleviated without changing the mapped subcarrier.

FIG. 5 schematically illustrates exemplary resource mapping consideringDMRS according to an example of the first embodiment. In this example,the modulated-symbol set transmitted in an OFDM symbol with DMRS in thenormal subframe is transmitted in an OFDM symbol with DMRS in DwPTS. Thefive subfigures of FIG. 5 are the normal DL subframe, the specialsubframe with configuration 1, 2, 6 or 7 as defined in Table 1, thespecial subframe with configuration 3, 4 or 8, the special subframe #1with configuration 9, and the special subframe #2 with configuration 9respectively, in which the dotted REs represent the CRS positions andthe gray REs represent the DMRS positions. It can be seen that themodulated-symbol set consisting of the modulated symbols #0-8, themodulated-symbol set consisting of the modulated symbols #9-17, themodulated-symbol set consisting of the modulated symbols #70-78, and themodulated-symbol set consisting of the modulated symbols #79-87 aremapped onto OFDM symbols with DMRS (the OFDM symbols #5, #6, #12 and#13) in the normal subframe respectively, and those modulated-symbolsets are also mapped onto OFDM symbols with DMRS in the specialsubframes. In addition, in this example, since the number of the OFDMsymbols with DMRS in DwPTS of the special subframes with configuration 9is less than that in the normal downlink subframe, the modulated-symbolsets transmitted in OFDM symbols with DMRS in the normal downlinksubframe can be transmitted cyclically in OFDM symbols with DMRS inDwPTS of multiple special subframes with configuration 9. As shown inFIG. 5, the special subframes #1 and #2 with configuration 9 bothtransmit two different modulated-symbol sets respectively. In addition,optionally, the modulated-symbol sets transmitted in OFDM symbolswithout DMRS in the normal downlink subframe can be transmittedcyclically in OFDM symbols without DMRS in DwPTS. According to theexample shown in FIG. 5, the same modulated symbol is mapped onto thesame subcarrier even if the DMRS positions are different in the normalDL and in the special subframe, which makes the symbol level combiningpossible. In addition, the performance imbalance among the modulatedsymbols transmitted in OFDM symbols with CRS is also alleviated.

FIG. 6 schematically illustrates exemplary resource mapping consideringboth CRS and DMRS according to an example of the first embodiment. Inthis example, the modulated-symbol set transmitted in an OFDM symbolwith CRS in the normal subframe is transmitted in an OFDM symbol withCRS in DwPTS, and the modulated-symbol set transmitted in an OFDM symbolwith DMRS in the normal subframe is transmitted in an OFDM symbol withDMRS in DwPTS. As for the modulated-symbol sets transmitted in OFDMsymbols without any RS in the normal subframe, some of them aretransmitted in OFDM symbols without any RS in DwPTS, and some of themare transmitted in OFDM symbols with RSs (e.g. DMRS) in DwPTS. In otherwords, at least one of the modulated-symbol sets transmitted in OFDMsymbols without any RS in a normal downlink subframe is transmitted inOFDM symbols with RSs in DwPTS. The modulated symbols supposed to betransmitted in RS positions in DwPTS are punctured in the RS positions,that is, they are not transmitted in the RS positions. In this manner,it is possible to make the repeated transmission of modulated symbolsmapped onto OFDM symbols with RS and without RS more balanced. It isnoted that the mapping manners for the modulated-symbol sets transmittedin OFDM symbols without any RS in the normal subframe illustrated in theexamples of FIG. 4, FIG. 5 and FIG. 6 can be exchanged with each other.

Four subfigures are shown in FIG. 6, which are the normal DL subframe,the special subframe #1 with configuration 9, the special subframe #2with configuration 9 and the special subframe #3 with configuration 9respectively, in which the dotted REs represent the CRS positions andthe gray REs represent the DMRS positions. As can be seen in FIG. 6, themodulated-symbol set consisting of the modulated symbols #12-19, themodulated-symbol set consisting of the modulated symbols #38-45, and themodulated-symbol set consisting of the modulated symbols #82-89 aremapped onto OFDM symbols with CRS (the OFDM symbols #4, #7 and #11) inthe normal subframe respectively, and those modulated-symbol sets arealso mapped onto OFDM symbols with CRS in the special subframes #1, #2and #3 respectively. The modulated-symbol set consisting of themodulated symbols #20-28, the modulated-symbol set consisting of themodulated symbols #29-37, the modulated-symbol set consisting of themodulated symbols #90-98, and the modulated-symbol set consisting of themodulated symbols #99-107 are mapped onto OFDM symbols with DMRS (theOFDM symbols #5, #6, #12 and #13) in the normal subframe respectively,and those modulated-symbol sets are mapped onto OFDM symbols with DMRSin the special subframes #1 and #3 respectively. The remainingmodulated-symbol sets are mapped onto OFDM symbols without any RS in thenormal subframe. Among these remaining modulated-symbol sets, themodulated-symbol set consisting of the modulated symbols #46-57 and themodulated-symbol set consisting of the modulated symbols #58-69 aremapped onto the OFDM symbols with DMRS in the special subframe #2. Sincethe DMRS positions (REs) in the special subframe #2 are used to transmitDMRS, the modulated symbols (#46, #51, #56, #58, #63 and #68 in thisexample) supposed to be mapped onto these RS positions are punctured inthese DMRS positions, i.e., are not transmitted in these positions, asshown by “x” in the special subframe #2 of FIG. 6. For othermodulated-symbols, they can be mapped onto OFDM symbols without any RSin the special subframes.

FIG. 7 schematically illustrates exemplary cyclic resource mappingaccording to an example of the first embodiment. In this example, themodulated-symbol sets transmitted in a normal DL subframe aretransmitted cyclically in DwPTS of multiple special subframes. Thegranularity is OFDM symbols in time domain. As shown in FIG. 7, themodulated symbol sets transmitted in OFDM symbols {#3, #4, #5, #6}, {#7,#8, #9, #10}, {#11, #12, #13, #0}, . . . in the normal DL subframe aretransmitted in special subframes #1, #2, #3, . . . cyclically.

In the above example, the RS REs can be handled in such a manner thatthe modulated symbols supposed to be transmitted in RS positions (REs)in DwPTS are punctured in the RS positions, and the REs in DwPTScorresponding to the RS REs in the normal subframe are left blank. FIG.8 schematically illustrates an example of handling RS REs according toan example of the present disclosure. In FIG. 8, the modulated-symbolsets mapped onto OFDM symbols {#8, #9, #10, #11} in the normal subframeare mapped onto OFDM symbols {#2, #3, #4, #5} in the special subframe.The modulated symbols #26, #29, #32 and #35 are punctured in the specialsubframe since the REs onto which those modulated symbols are supposedto be mapped in the special subframe are CRS REs, as shown by “x” in thespecial subframe. In addition, the REs represented by “B” in the OFDMsymbol #5 of the special subframe are corresponding to the CRS REs inthe OFDM symbol #11 of the normal subframe according to the abovemapping manner; therefore, those REs represented by “B” in the OFDMsymbol #5 of the special subframe are left blank.

According to the example shown in FIG. 7 and FIG. 8, the transmittingsymbols are almost with complete balanced performance. In addition,there is no need to consider the RS positions, and thus it is easy toimplement. It is noted that the manner of handling RS REs illustrated inFIG. 8 can also be applied to other examples or embodiments of thepresent disclosure if appropriate.

In the first embodiment, there is also provided a wireless communicationdevice (first wireless communication) for performing the above methods.FIG. 9 is a block diagram illustrating a wireless communication device900 according to the first embodiment of the present disclosure. Thewireless communication device 900 can comprise a transmitting unit 901which is configured to transmit a data packet repeatedly in multiplesubframes including at least one normal subframe and at least onespecial subframe to another wireless communication device (secondwireless communications device), wherein the available resources in thespecial subframe are different from that in the normal subframe, thedata packet includes multiple modulated symbols which are divided intomultiple modulated-symbol sets, in each subframe, each OrthogonalFrequency Division Multiplexing (OFDM) symbol is mapped by one of themodulated-symbol sets, and in every subframe, the modulated symbols inthe same modulated-symbol set are mapped onto Resource Elements (REs) inone OFDM symbol in a fixed order. It is noted that the aboveexplanations for the methods are also applied to the device here, whichwill not be repeated again.

The wireless communication device 900 according to the presentdisclosure may optionally include a CPU (Central Processing Unit) 910for executing related programs to process various data and controloperations of respective units in the wireless communication device 900,a ROM (Read Only Memory) 913 for storing various programs required forperforming various process and control by the CPU 910, a RAM (RandomAccess Memory) 915 for storing intermediate data temporarily produced inthe procedure of process and control by the CPU 910, and/or a storageunit 917 for storing various programs, data and so on. The abovetransmitting unit 901, CPU 910, ROM 913, RAM 915 and/or storage unit 917etc. may be interconnected via data and/or command bus 920 and transfersignals between one another.

Respective units as described above do not limit the scope of thepresent disclosure. According to one implementation of the disclosure,the functions of the above transmitting unit 901 may be implemented byhardware, and the above CPU 910, ROM 913, RAM 915 and/or storage unit917 may not be necessary. Alternatively, the functions of the abovetransmitting unit 901 may also be implemented by functional software incombination with the above CPU 910, ROM 913, RAM 915 and/or storage unit917 etc.

Accordingly, at the receiving side, the first embodiment provides awireless communication method 1000 performed by a wireless communicationdevice (second communication device) as shown in FIG. 10. The wirelesscommunication method 1000 comprising a step 1001 of receiving a datapacket which is repeatedly transmitted in multiple subframes includingat least one normal subframe and at least one special subframe fromanother wireless communication device (first communication device),wherein the available resources in the special subframe are differentfrom that in the normal subframe, the data packet includes multiplemodulated symbols which are divided into multiple modulated-symbol sets,in each subframe, each Orthogonal Frequency Division Multiplexing (OFDM)symbol is mapped by one of the modulated-symbol sets, and in everysubframe, the modulated symbols in the same modulated-symbol set aremapped onto Resource Elements (REs) in one OFDM symbol in a fixed order.It is noted that the above explanations for the methods at thetransmitting side are also applied to the method 1000, which will not berepeated again.

In addition, in the first embodiment, there is also provided a wirelesscommunication device (second wireless communication) for performing theabove method at the receiving side. FIG. 11 is a block diagramillustrating a wireless communication device 1100 at the receiving sideaccording to the first embodiment of the present disclosure. Thewireless communication device 1100 can comprise a receiving unit 1101configured to receive a data packet which is repeatedly transmitted inmultiple subframes including at least one normal subframe and at leastone special subframe from another wireless communication device (firstwireless communications device), wherein the available resources in thespecial subframe are different from that in the normal subframe, thedata packet includes multiple modulated symbols which are divided intomultiple modulated-symbol sets, in each subframe, each OrthogonalFrequency Division Multiplexing (OFDM) symbol is mapped by one of themodulated-symbol sets, and in every subframe, the modulated symbols inthe same modulated-symbol set are mapped onto Resource Elements (REs) inone OFDM symbol in a fixed order. It is noted that the aboveexplanations for the methods are also applied to the device here, whichwill not be repeated again.

The wireless communication device 1100 according to the presentdisclosure may optionally include a CPU (Central Processing Unit) 1110for executing related programs to process various data and controloperations of respective units in the wireless communication device1100, a ROM (Read Only Memory) 1113 for storing various programsrequired for performing various process and control by the CPU 1110, aRAM (Random Access Memory) 1115 for storing intermediate datatemporarily produced in the procedure of process and control by the CPU1110, and/or a storage unit 1117 for storing various programs, data andso on. The above receiving unit 1101, CPU 1110, ROM 1113, RAM 1115and/or storage unit 1117 etc. may be interconnected via data and/orcommand bus 1120 and transfer signals between one another.

Respective units as described above do not limit the scope of thepresent disclosure. According to one implementation of the disclosure,the functions of the above receiving unit 1101 may be implemented byhardware, and the above CPU 1110, ROM 1113, RAM 1115 and/or storage unit1117 may not be necessary. Alternatively, the functions of the abovereceiving unit 1101 may also be implemented by functional software incombination with the above CPU 1110, ROM 1113, RAM 1115 and/or storageunit 1117 etc.

Second Embodiment

In some application scenarios, for example, for control channel forpieces of MTC UE in enhanced coverage, multiple repetitions can betransmitted in one subframe as shown in FIG. 12 which schematicallyillustrates multiple repetitions transmitted in one subframe. FIG. 12exemplarily shows that 6 repetitions are transmitted in one subframe.For this case, the second embodiment of the present disclosure providesa wireless communication method performed by a wireless communicationdevice (first communication device). The wireless communication methodcan comprises a step of transmitting a data packet repeatedly inmultiple subframes including at least one normal subframe and at leastone special subframe to another wireless communication device (secondcommunication device), wherein the available resources in the specialsubframe are different from that in the normal subframe. The wirelesscommunication method in the second embodiment can have the sameflowchart as shown in FIG. 2 for the first embodiment, and the detailsdescribed for the first embodiment may also be applied to the secondembodiment unless the context indicates otherwise.

In the second embodiment, multiple repetitions of the data packet aretransmitted in each subframe, and in each subframe, differentrepetitions are mapped onto REs with cyclic shift. The shift granularitycan be modulated symbol level. FIG. 13 illustrates an example of theresource mapping with cyclic shift according to the second embodiment,in which 6 repetitions in one subframe is taken as an example. The leftsubfigure of FIG. 13 shows normal mapping without shift in a normalsubframe, and the right subfigure shows modified mapping with cyclicshift in the normal subframe. In the example of FIG. 13, each PRB paircomprises three subcarriers for transmitting one repetition, and in eachPRB pair, modulated symbols of the data packet are mapped onto REs forexample in an order of mapping first in the frequency domain and then inthe time domain. The difference between the normal mapping and themodified mapping is as follows. In the normal mapping, each repetitionis mapped onto one PRB pair in exactly the same manner; however, in themodified mapping, among the repetitions in one subframe, cyclic shift isapplied to the mapping. As shown in the modified mapping of FIG. 13,cyclic shift of 6 modulated symbols is applied between adjacentrepetitions. It is noted that the second embodiment is not limited tothe specific mapping manner shown in FIG. 13. For example, the cyclicshift is not limited to 6 modulated symbols, but can be any appropriatenumber of modulated symbols, and the number of subcarriers in each PRBpair is not limited to 3.

According to the second embodiment, it is possible to always truncatethe same part of the normal subframe to be mapped onto special subframeswhile remaining balanced performance among the modulated symbols. Asshown in the modified mapping of FIG. 13, the modulated symbols of thefirst three OFDM symbols of the repeated DL channel of the normal symbolcan always be truncated to be mapped onto DwPTS of special subframes. Itcan be seen that almost every modulated symbol can be included in thetruncated part due to the cyclic shift; therefore balanced performancecan be obtained among the modulated symbols of the data packet. Incontrast, if the first three OFDM symbols in the normal mapping arealways truncated to be mapped onto special subframes, then the modulatedsymbols #0-8 can be transmitted in the special subframes, resulting inimbalanced performance among the modulated symbols of the data packet.

It is noted that, in the second embodiment, the normal subframes canalso adopt other mapping manners such as the normal mapping shown inFIG. 13, but the special subframes employ the mapping with cyclic shift.In addition, some implementations of the first embodiment can becombined with the second embodiment unless the context indicatesotherwise.

In the second embodiment, there is also provided a wirelesscommunication device (first wireless communications device) comprising atransmitting unit configured to transmit a data packet repeatedly inmultiple subframes including at least one normal subframe and at leastone special subframe to another wireless communication device, whereinthe available resources in the special subframe are different from thatin the normal subframe, multiple repetitions of the data packet aretransmitted in each subframe, and in each special subframe, differentrepetitions are mapped onto Resource Elements (REs) with cyclic shift.The first wireless communication device in the second embodiment canhave the same structure as that in the first embodiment shown in FIG. 9.

Accordingly, at the receiving side, the second embodiment also providesa wireless communication method performed by a wireless communicationdevice (second communication device). The wireless communication methodhere can have the same flowchart as shown in FIG. 10 and comprise a stepof receiving a data packet which is repeatedly transmitted in multiplesubframes including at least one normal subframe and at least onespecial subframe from another wireless communication device (firstcommunication device), wherein the available resources in the specialsubframe are different from that in the normal subframe, multiplerepetitions of the data packet are transmitted in each subframe, and ineach special subframe, different repetitions are mapped onto ResourceElements (REs) with cyclic shift. It is noted that the aboveexplanations for the method at the transmitting side are also applied tothe method at the receiving side, which will not be repeated again.

Further, in the second embodiment, there is also provided a wirelesscommunication device (second wireless communications device) for thereceiving side comprising a receiving unit configured to receive a datapacket which is repeatedly transmitted in multiple subframes includingat least one normal subframe and at least one special subframe fromanother wireless communication device (first wireless communicationdevice), wherein the available resources in the special subframe aredifferent from that in the normal subframe, multiple repetitions of thedata packet are transmitted in each subframe, and in each specialsubframe, different repetitions are mapped onto Resource Elements (REs)with cyclic shift. The second wireless communication device in thesecond embodiment can have the same structure as that in the firstembodiment shown in FIG. 11.

The present disclosure can be realized by software, hardware, orsoftware in cooperation with hardware. Each functional block used in thedescription of each embodiment described above can be partly or entirelyrealized by an LSI such as an integrated circuit, and each processdescribed in the each embodiment may be controlled partly or entirely bythe same LSI or a combination of LSIs. The LSI may be individuallyformed as chips, or one chip may be formed so as to include a part orall of the functional blocks. The LSI may include a data input andoutput coupled thereto. The LSI here may be referred to as an IC, asystem LSI, a super LSI, or an ultra LSI depending on a difference inthe degree of integration. However, the technique of implementing anintegrated circuit is not limited to the LSI and may be realized byusing a dedicated circuit, a general-purpose processor, or aspecial-purpose processor. In addition, a FPGA (Field Programmable GateArray) that can be programmed after the manufacture of the LSI or areconfigurable processor in which the connections and the settings ofcircuit cells disposed inside the LSI can be reconfigured may be used.The present disclosure can be realized as digital processing or analogueprocessing. If future integrated circuit technology replaces LSIs as aresult of the advancement of semiconductor technology or otherderivative technology, the functional blocks could be integrated usingthe future integrated circuit technology. Biotechnology can also beapplied.

It is noted that the present disclosure intends to be variously changedor modified by those skilled in the art based on the descriptionpresented in the specification and known technologies without departingfrom the content and the scope of the present disclosure, and suchchanges and applications fall within the scope that claimed to beprotected. Furthermore, in a range not departing from the content of thedisclosure, the constituent elements of the above-described embodimentsmay be arbitrarily combined.

What is claimed is:
 1. A communication device comprising: a receiver,which, in operation, receives a modulation symbol set that istransmitted with repetitions in multiple subframes, the modulationsymbol set being mapped to a first Orthogonal Frequency DivisionMultiplexing (OFDM) symbol, to which a reference signal is mapped, in afirst subframe, and being mapped to a second OFDM symbol, to which thereference signal is mapped and which is different from the first OFDMsymbol, in a second subframe that is different from the first subframe;and circuitry, which is coupled to the receiver and which, in operation,process the received modulation symbol set.
 2. The communication deviceaccording to claim 1, wherein the receiver, in operation, receivesanother modulation symbol set that is transmitted with repetitions inthe multiple subframes, the another modulation symbol set being mappedto a third OFDM symbol, to which a reference signal is not mapped, inthe first subframe, and being mapped to a fourth OFDM symbol, to whichthe reference signal is not mapped and which is different from the thirdOFDM symbol, in the second subframe, and the circuitry, in operation,process the received another modulation symbol set.
 3. The communicationdevice according to claim 1, wherein the receiver, in operation,receives another modulation symbol set that is transmitted withrepetitions in the multiple subframes, the another modulation symbol setbeing mapped to a third OFDM symbol, in the first subframe, and beingmapped to a fourth OFDM symbol, to which another reference signal ismapped and which is different from the third OFDM symbol, in the secondsubframe, wherein one or more symbols of the another modulation symbolset, which correspond to one or more resource elements of the fourthOFDM symbol, are punctured, and the another reference signal is mappedto the one or more resource elements, and the circuitry, in operation,process the received another modulation symbol set.
 4. The communicationdevice according to claim 1, wherein the first and second subframes areconfigured in a Frequency Division Duplexing (FDD).
 5. The communicationdevice according to claim 1, wherein the first and second subframes areconfigured in a Time Division Duplexing (TDD) and include a normalsubframe and a special subframe.
 6. The communication device accordingto claim 1, wherein the receiver, in operation, receives the modulationsymbol set being mapped to the first OFDM symbol and the second OFDMsymbol in a fixed order.
 7. A communication method, comprising:receiving a modulation symbol set that is transmitted with repetitionsin multiple subframes, the modulation symbol set being mapped to a firstOrthogonal Frequency Division Multiplexing (OFDM) symbol, to which areference signal is mapped, in a first subframe, and being mapped to asecond OFDM symbol, to which the reference signal is mapped and which isdifferent from the first OFDM symbol, in a second subframe that isdifferent from the first subframe; and processing the receivedmodulation symbol set.
 8. The communication method according to claim 7,wherein the receiving includes receiving another modulation symbol setthat is transmitted with repetitions in the multiple subframes, theanother modulation symbol set being mapped to a third OFDM symbol, towhich a reference signal is not mapped, in the first subframe, and beingmapped to a fourth OFDM symbol, to which the reference signal is notmapped and which is different from the third OFDM symbol, in the secondsubframe, and the processing includes processing the received anothermodulation symbol set.
 9. The communication method according to claim 7,wherein the receiving includes receiving another modulation symbol setthat is transmitted with repetitions in the multiple subframes, theanother modulation symbol set being mapped to a third OFDM symbol, inthe first subframe, and being mapped to a fourth OFDM symbol, to whichanother reference signal is mapped and which is different from the thirdOFDM symbol, in the second subframe, wherein one or more symbols of theanother modulation symbol set, which correspond to one or more resourceelements of the fourth OFDM symbol, are punctured, and the anotherreference signal is mapped to the one or more resource elements, and theprocessing includes processing the received another modulation symbolset.
 10. The communication method according to claim 7, wherein thefirst and second subframes are configured in a Frequency DivisionDuplexing (FDD).
 11. The communication method according to claim 7,wherein the first and second subframes are configured in a Time DivisionDuplexing (TDD) and include a normal subframe and a special subframe.12. The communication method according to claim 7, wherein the receivingincludes receiving the modulation symbol set being mapped to the firstOFDM symbol and the second OFDM symbol in a fixed order.